* [PATCH 01/13] dyndbg: fix static_branch manipulation
[not found] <20220217034829.64395-1-jim.cromie@gmail.com>
@ 2022-02-17 3:48 ` Jim Cromie
0 siblings, 0 replies; 2+ messages in thread
From: Jim Cromie @ 2022-02-17 3:48 UTC (permalink / raw)
To: jbaron, gregkh, linux-kernel, dri-devel, amd-gfx, intel-gvt-dev,
intel-gfx
Cc: daniel.vetter, seanpaul, robdclark, linux, joe, Jim Cromie,
vincent.whitchurch, stable
In https://lore.kernel.org/lkml/20211209150910.GA23668@axis.com/
Vincent's patch commented on, and worked around, a bug toggling
static_branch's, when a 2nd PRINTK-ish flag was added. The bug
results in a premature static_branch_disable when the 1st of 2 flags
was disabled.
The cited commit computed newflags, but then in the JUMP_LABEL block,
did not use that result, but used just one of the terms in it. Using
newflags instead made the code work properly.
This is Vincents test-case, reduced. It needs the 2nd flag to work
properly, but it's explanatory here.
pt_test() {
echo 5 > /sys/module/dynamic_debug/verbose
site="module tcp" # just one callsite
echo " $site =_ " > /proc/dynamic_debug/control # clear it
# A B ~A ~B
for flg in +T +p "-T #broke here" -p; do
echo " $site $flg " > /proc/dynamic_debug/control
done;
# A B ~B ~A
for flg in +T +p "-p #broke here" -T; do
echo " $site $flg " > /proc/dynamic_debug/control
done
}
pt_test
Fixes: 84da83a6ffc0 dyndbg: combine flags & mask into a struct, simplify with it
CC: vincent.whitchurch@axis.com
CC: stable@vger.kernel.org
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
lib/dynamic_debug.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index dd7f56af9aed..a56c1286ffa4 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -211,10 +211,11 @@ static int ddebug_change(const struct ddebug_query *query,
continue;
#ifdef CONFIG_JUMP_LABEL
if (dp->flags & _DPRINTK_FLAGS_PRINT) {
- if (!(modifiers->flags & _DPRINTK_FLAGS_PRINT))
+ if (!(newflags & _DPRINTK_FLAGS_PRINT))
static_branch_disable(&dp->key.dd_key_true);
- } else if (modifiers->flags & _DPRINTK_FLAGS_PRINT)
+ } else if (newflags & _DPRINTK_FLAGS_PRINT) {
static_branch_enable(&dp->key.dd_key_true);
+ }
#endif
dp->flags = newflags;
v4pr_info("changed %s:%d [%s]%s =%s\n",
--
2.35.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH 01/13] dyndbg: fix static_branch manipulation
[not found] <20220301164629.3814634-1-jim.cromie@gmail.com>
@ 2022-03-01 16:46 ` Jim Cromie
0 siblings, 0 replies; 2+ messages in thread
From: Jim Cromie @ 2022-03-01 16:46 UTC (permalink / raw)
To: jbaron, gregkh, daniel.vetter, seanpaul, robdclark, linux-kernel,
dri-devel, amd-gfx, intel-gvt-dev, intel-gfx
Cc: Jim Cromie, vincent.whitchurch, stable
In https://lore.kernel.org/lkml/20211209150910.GA23668@axis.com/
Vincent's patch commented on, and worked around, a bug toggling
static_branch's, when a 2nd PRINTK-ish flag was added. The bug
results in a premature static_branch_disable when the 1st of 2 flags
was disabled.
The cited commit computed newflags, but then in the JUMP_LABEL block,
did not use that result, but used just one of the terms in it. Using
newflags instead made the code work properly.
This is Vincents test-case, reduced. It needs the 2nd flag to work
properly, but it's explanatory here.
pt_test() {
echo 5 > /sys/module/dynamic_debug/verbose
site="module tcp" # just one callsite
echo " $site =_ " > /proc/dynamic_debug/control # clear it
# A B ~A ~B
for flg in +T +p "-T #broke here" -p; do
echo " $site $flg " > /proc/dynamic_debug/control
done;
# A B ~B ~A
for flg in +T +p "-p #broke here" -T; do
echo " $site $flg " > /proc/dynamic_debug/control
done
}
pt_test
Fixes: 84da83a6ffc0 dyndbg: combine flags & mask into a struct, simplify with it
CC: vincent.whitchurch@axis.com
CC: stable@vger.kernel.org
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
lib/dynamic_debug.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index dd7f56af9aed..a56c1286ffa4 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -211,10 +211,11 @@ static int ddebug_change(const struct ddebug_query *query,
continue;
#ifdef CONFIG_JUMP_LABEL
if (dp->flags & _DPRINTK_FLAGS_PRINT) {
- if (!(modifiers->flags & _DPRINTK_FLAGS_PRINT))
+ if (!(newflags & _DPRINTK_FLAGS_PRINT))
static_branch_disable(&dp->key.dd_key_true);
- } else if (modifiers->flags & _DPRINTK_FLAGS_PRINT)
+ } else if (newflags & _DPRINTK_FLAGS_PRINT) {
static_branch_enable(&dp->key.dd_key_true);
+ }
#endif
dp->flags = newflags;
v4pr_info("changed %s:%d [%s]%s =%s\n",
--
2.35.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
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2022-02-17 3:48 ` [PATCH 01/13] dyndbg: fix static_branch manipulation Jim Cromie
[not found] <20220301164629.3814634-1-jim.cromie@gmail.com>
2022-03-01 16:46 ` Jim Cromie
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